“We believe the plaintiffs are correct in their assertion that the Illinois Constitution upholds marriage equality for same sex couples just as it does for opposite sex couples,” spokeswoman Sally Daly said in an email.

The Illinois Attorney General’s office has also said it plans to file a brief in support of the lawsuits, and Gov. Pat Quinn has voiced his support for gay marriage.

ACLU attorney John Knight said today that he wasn’t surprised that the state’s attorney agrees with the argument, particularly since Orr himself has made clear that he believes same-sex couples should be granted marriage licenses.

“This is good news,” Knight said of today’s filing. “It certainly brings us closer to the day we’re looking for.”

The next hearing in this case will be June 21, when a motion to combine the two lawsuits will be heard by Judge Moshe Jacobius, Presiding Judge of the Chancery Division of the Circuit Court of Cook County.

It’s unclear how the case will proceed.

In other states, outside groups that oppose gay marriage have often stepped in to defend lawsuits like this, and the Chicago-based Thomas More Society has already said it would provide any support it could to defend the constitutionality of the state’s marriage laws.

"Today's announcement by State's Attorney Anita Alvarez makes it clear that this lawsuit was an 'inside job' from the beginning, a crass political move to force same-sex marriage on all Illinoisans without providing residents of the other 101 counties an opportunity to be heard," Thomas More Society attorney Peter Breen said.

The society is preparing legal papers to allow the group to defend the ban in court.

Currently six states and the District of Columbia allow same-sex marriages.

North Carolina recently became the 31st state to ban gay marriage with a constitutional amendment, and while national polls have shown a strong swing toward acceptance of same-sex marriage, it has been defeated in all 32 states where it has been on the ballot.rhuppke@tribune.com

Illinois Attorney General Lisa Madigan’s office has filed a notice in Cook County Circuit Court saying it will present arguments in support of two lawsuits that question the constitutionality of the state's gay marriage ban.

A judge entered a not guilty plea Tuesday for a suspended Broward Sheriff's deputy accused of shooting a man in the leg during an off-duty confrontation at the Hollywood home the victim shared with his girlfriend.